1. Field of the Invention
The present invention relates to a network node for a communication network, where the communication network comprises a first subnetwork and a second subnetwork connected to the first subnetwork, in which the first subnetwork uses a spanning tree protocol and the second subnetwork uses a second protocol that differs from the protocol of the first subnetwork, with the network node being configured as an element of the second subnetwork and being configured to communicate within the second subnetwork.
2. Description of the Related Art
Publication WO 2008/119626 A2, for example, discloses network nodes for an industrial LAN (Local Area Network) which is designed as a ring. This industrial LAN is connected to an office LAN which is designed as a complex, meshed network and on which what is referred to as a Radio Spanning Tree Protocol (RSTP) in accordance with IEEE Standard 802.1w is installed. With the aid of this RSTP protocol, despite many redundant paths in an office Local Area Network (LAN), communication loops within this network can be successfully avoided. Using this protocol, the corresponding communication paths can be adapted even after faults, such as the failure of lines, ports and/or network nodes.
Problems arise in the prior art during the linkage of such an office LAN, which uses the RSTP protocol, and an industrial LAN on which for example, an industry-compatible realtime-capable protocol is installed, if such a reconfiguration by the RSTP protocol occurs. In such cases, this can lead to problems in the interworking of the RSTP protocol and the protocol in the industrial LAN which, for example, can delay communication in the industrial LAN or even interrupt the communication.